On 4 Jun 1993, Sydney Shall wrote:
> Recent discusion has touched upon the question as to whether cell division
> is related
> to human ageing. The answer is clearly that cell division is related
> to human ageing. There is some indirect evidence for this statement;
> but there is direct evidence
> in the human genetic condition known as Werner's Syndrome.
> In this condition, there is severe premature ageing and the life-span
> is approximately halved. Cells from these patients show a much
> reduced (between 3 and 5 fold) ability to proliferate, thus it
> is now clear that there is some, currently unclear connection between
> cell proliferation and human ageing.
>> Sydney Shall
>>> **************************************************************************
>> **************************************************************************
>>>> Sydney SHALL,
> Laboratory of Cell and Molecular Biology,
> Biology Building,
> University of Sussex,
> Brighton,
> East Sussex BN1 9QG,
> ENGLAND.
>> Telephone: +44.273.67.83.03
>> FAX: +44.273.67.83.33
>> E-Mail:
>> Janet: BAFA1 at uk.ac.sussex.central>> Elsewhere: BAFA1 at central.sussex.ac.uk>> EARN/BITNET: BAFA1%sussex.central at ukacrl>>> *******************************************************************************
>> *******************************************************************************
One powerful model is that ageing is related also to deletions to
mitochondrial DNA. A common deletion that is seen in mitochondrial
myopathies and also in aging post mitotic tissues such as muscle, cuts out
about 2/3 of the oxidative phosphorylation pathway and results in depleted
energy production and disordered release of free radicals. Rapidly
dividing cells may eliminate defective mitochondria by active selection.
We've recently identified this deletion in testis biopsies from men with
spermatogenic failure: this is consistent with the hypothesis that some
forms of male infertility are due to premature testis ageing. The link
between free radicals and sperm dysfunction is well established. If
netters are interested in this area email me directly and I can give more
info.
Jim Cummins Murdoch University Western Australia>